Canon EOS 5D Mark III Digital Camera Review$3,499.00
We found that the Canon 5D Mark III's full frame image sensor produced some of the best results we've seen at the minimum ISO of 100. At that speed the camera returned just 0.39% average chroma noise, and 0.41% luminance noise, which is a fluctuation that is imperceptible at any reasonable viewing distance. More on how we test noise.
The noise reduction on the 5D Mark III begins to kick in and really impact fine image detail at ISO 400 and above. The impact of this tactic will largely depend on what your final plans for the image are. If you're planning of taking an image and printing it to a very large size, or cropping it while maintaining fine detail in text, fabrics, leaves, and hair, then the noise reduction is going to impact the final quality of your shot. In these cases we'd recommend shooting with noise reduction off (preferably in the RAW format) and tweaking noise more carefully in a post-processing editing program.
The Canon 5D Mark III allows you to select from a native ISO range of 100-25600 in whole, half, and 1/3-stop increments. That can be expanded in either direction, as well, allowing users to select ISO speeds anywhere from 50-102400. ISO speed can be set on the camera via the menu, or by utilizing the direct ISO button on the top plate of the camera, identical in location and usage to the 5D Mark II.